Phase shifters are used, for example, for trimming the delay time of microwave signals in passive or active networks. As a known principle, the delay time of a line is used to trim the phase angle of a signal and, in consequence, a variable phase angle means that the lines have different electrically effective lengths.
For applications in antennas with an electrically adjustable notch in the polar diagram, the signals have different delay times to the individual radiating elements, for example dipoles. The difference in the delay times between two adjacent radiating elements is approximately the same for a specific notch angle in an array of radiating elements arranged vertically one above the other. This delay time difference is also increased for larger notch angles. If the phase angles of the individual radiating elements are varied by means of phase shift assemblies, then this is an antenna with an adjustable electrical notch in the polar diagram.
According to WO 96/37922, a phase shift is known which has electrically moveable plates in order to produce a phase difference between different outputs, but at least between two outputs. This has the disadvantage that the movement of the dielectric plates also changes the impedance of the respectively affected lines, and the way in which the power of the signals is shared depends on the setting of the phase shifter.
The prior publication WO 96/37009 proposes a symmetrical line branching system in order to emit the same power at both ends of this line. This can be done provided that both ends are terminated by the characteristic impedance of this line. Comparable solutions of these technical principles have already been used for a long time for mobile radio antennas. However, these solutions have the disadvantage that only two radiating elements can be supplied, and they also still receive the same power. A further disadvantage is the moving electrically conductive connection between the input and the respective lines. Electrically high-quality contacts may exhibit undesirable nonlinearities.
In principle, it is also known for a number of phase shifters to be integrated in one antenna. Such phase shifters can supply the individual radiating elements in the entire antenna arrangement. Individual radiating elements have different phase differences, and the phase shift assembly settings differ for the individual radiating elements. This necessitates complex mechanical step-up transmission systems such as illustrated, in principle, in FIG. 1, which shows a corresponding design according to the prior art.
To this end, and in order to illustrate the prior art, FIG. 1 shows, schematically, an antenna array 1 having, for example, five dipole elements 1a, 1b, 1c, 1d, 1e which are fed via a feed input 5.
The feed input 5 is followed by a distribution network (“∥S∥”) 7 which, in the illustrated example, supplies two RF phase shift assemblies 9′, 9″ with each of the two phase shift assemblies supplying two dipoles.
A feed line 13 passes from the distribution network 7 to a central dipole radiating element 1c, which is driven without any phase shift.
The other dipoles are supplied with different phases, depending on the setting of the phase shift assembly 9, with, for example:    the dipole 1a supplied with a phase +2Φ,    the dipole radiating element 1b supplied with a phase +1φ,    the central dipole radiating element 1c supplied with the phase φ=0,    the fourth dipole radiating element 1d supplied with the phase −1φ, and    the last dipole radiating element 1e supplied with the phase −2φ.
In consequence, the phase shift assembly 9′ therefore ensures a split of +2φ and −2φ, and the second phase shift assembly 9″ ensures a phase shift of +φ and −φ, for the respectively associated dipole radiating elements 1a, 1e and 1b, 1d, respectively. A correspondingly different setting for the phase shift assemblies 9′, 9″ can then be ensured by a mechanical actuating drive 17. In this example, a comparatively complex mechanical step-up transmission drive 17 is used to produce the different phase differences required for the respective individual radiating elements.
A phase shift assembly of this generic type is known from PATENT ABSTRACTS OF JAPAN Vol. 1998 No. 1, Jan. 30, 1998 (1998-01-30) & JP 09 246846 A (NTT IDO TSUSHINMO KK), Sep. 19, 1997 (1997-09-19). This prior publication covers two stripline segments which are in the form of circle segments and are arranged offset with respect to one another in the circumferential direction and at a different distance from a central center point. A tapping element can be moved about this center point, engaging with the respective stripline segment. The tapping element in this case comprises two radial elements. The two radial elements are offset with respect to one another with an angular separation in plan view, and are connected to one another at the center point, which lies on their pivoting axis.
Exemplary illustrative non-limiting implementations of the technology herein provide an improved phase shift assembly which has a simpler design and, particularly in the case of an antenna array using at least four radiating elements, allows an improvement to the control and setting of the phases of the individual radiating elements. In this case, power sharing, in particular in pairs, between at least four radiating elements is preferably intended to be possible at the same time.
Exemplary illustrative non-limiting implementations of the technology herein provide a phase shift assembly which is compact and, has a higher integration density. Furthermore, additional connection lines, solder points and transformation means for providing the power sharing are minimized. There is also no need for the step-up transmission system to produce and to set the different phase angles for the radiating elements.
Exemplary illustrative non-limiting implementations of the technology herein provide at least two stripline segments in the form of circle segments. They interact with a tapping element. The tapping element is connected to a feed point, and forms a moveable tap or coupling point in the overlapping area with the respective circular stripline segment. A common connection line, which extends as far as the outermost circle segment, leads from the common feed point to the individual circle segments.
As mentioned, the stripline segments may be in the form of circle segments. The stripline sections may, in general terms, also be provided arranged concentrically with respect to one another. Such arrangement may also include stripline sections which run in a straight line and are arranged parallel to one another (namely for the situation where the radius of the stripline sections which are in the form of circle segments becomes infinite).
One exemplary simple refinement comprises providing a tapping element which passes over a number of stripline segments in the form of circle segments, like a radially running pointer. Such arrangement hence forms a number of associated tapping points which are located one behind the other in individual stripline segments.
A type of bridge structure is also possible. Connection lines which run in the same direction are arranged one above the other when seen in a horizontal side view. They can be moved about a common pivoting axis, and are rigidly connected to form a common tapping element, which can be handled.
The feed to the common rotation point is preferably capacitive. The tapping point between the tapping element and the respective circular stripline segment is also capacitive.
Exemplary illustrative non-limiting implementations of the technology herein also allow transmitting power to be shared, for example, in such a manner that the power decreases or increases from the inner to the outer circular stripline segment or, if required, even allows the power to all the stripline segments to remain more or less constant.
Furthermore, it has been found to be advantageous for the radio-frequency phase shift assembly to be formed on a metallic base plate, which is preferably formed by the reflector of the antenna. In addition, it has been found to be advantageous for the phase shift assembly to be shielded by a metallic cover.
The distances between the circle segments may differ. The diameter of the stripline segments preferably increases by a constant factor from the inside to the outside. The distances between the circle segments may in this case preferably transmit 0.1 to about 1.0 times the transmitter RF wavelength.
One simple exemplary implementation of the phase shift assembly can also allow the circle segments and connection lines to be formed together with a cover as triplate lines.